I remember the scene of my favorite bird-chasing experience well. The Gregory Canyon trail in Boulder, bordered by Gambel’s oak and mixed conifer forest, would play host to a male Scarlet Tanager the summer of 2007. The Scarlet Tanager is an eastern species, but there are times when a vagrant will penetrate into the west. This reminds me of a phrase I have heard often from birders: birds don’t read the range maps in field guides. In saying this, I call to mind the Streak-backed Oriole in Loveland, CO, or the Lawrence’s Goldfinch in Mesa County, CO.

Cherry red with coal wings, the Scarlet Tanager is the only Piranga species to have a crook, a “tooth”, in its upper mandible. This particular bird spent its evening flirting with a female Western Tanager. Other birders joke that females of his own species wouldn’t take him, so he came out west looking for a cowgirl. On a more serious note, we ponder if such a pairing would actually be successful. What would the young look like? Furthermore, what would they sound like?

Scarlet Tanager, colored pencil 

Such chases are more than a tick on a state list. They represent moments that belong to science—the mystery of bird movement, of beasts with wings. What are some of your favorite bird-chasing experiences? If your target bird proved an exceptional vagrant, take a moment to discuss the forces causing a bird to deviate from its “normal” range. Any thoughts on where the February 2008 White-crested Elaenia discovered in South Texas came from?